Unsaturated polyester resin syrups are employed in the production of coatings, molded casts and hand lay-up products such as building sheets, automobile fenders, furniture, plumbing fixtures, tub/shower stall units, ductwork, boats, electrical component housings, electrical circuit boards and the like.
It is known in the art that a wide variety of extenders may be incorporated into an unsaturated polyester resin syrup composition. A particular extender material selected is generally dependent upon a number of considerations including strength, flammability, texture, cost, etc. For example, in applicant's prior U.S. Pat. No. 3,978,018, an aqueous alkali stabilized colloidal silica and other reinforcing and non-reinforcing extender materials are disclosed for addition to a resin syrup to obtain a composition which possesses a low fuel content and a low flame spread.
In applicant's U.S. Pat. Nos. 4,011,195 and 4,013,614, a composition which also possesses a low fuel content and a low flame spread is obtained by adding an aqueous alkali metal silicate and other reinforcing and non-reinforcing extender materials to an unsaturated polyester resin syrup.
In applicant's U.S. Pat. Nos. 4,192,791, 4,347,331 and 4,402,633, aluminum compounds are employed as extenders for unsaturated polyester resin syrups.
However, increases in viscosity upon the addition of prior art extenders has heretofore precluded sprayability. The composition of the present invention provides an economical extender for use with unsaturated polyester resin syrups with limited viscosity increase. The reactive extender according to the present invention also affords improved process conditions for use of same leading to improved products.